Fix CameraDeviceDelegateTest.StopBeforeOpened.

Bug: chromium:978278, b:135894873
Test: Passes CameraDeviceDelegateTest.StopBeforeOpened 100 times in a
row.

Change-Id: I83fed9f89580aefca4501c2030bbeec2814e246b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1675354
Reviewed-by: Ricky Liang <jcliang@chromium.org>
Commit-Queue: Shik Chen <shik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672030}
2 files changed